JP2007019698A - Ring type redundant communication path control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that when a communication path is switched in the case of a trouble, a loop is formed as the result of path switching based upon the erroneous detection of the trouble by making the communication path lengthy by using a ring type lengthy communication path. <P>SOLUTION: A control frame imparted with a device identifier array is transmitted and received inward and outward between transfer devices constituting the ring type lengthy communication path to detect a trouble and specify its occurrence place from the received device identifier array, when the trouble is detected, a transfer device 1 which should open a control port waits for an opening instruction from a transfer device having closed a control port and performs closure processing for the control port. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a line control technique for making a communication path redundant and switching a communication line according to a failure condition, and in particular, a ring-type redundant communication path control method suitable for a network realizing redundancy by a ring-type redundant communication path It is about.

  Currently, in a WAN (Wide Area Network) service provided by a telecommunications carrier, in order to improve the communication reliability of the user, the route within the telecommunications carrier network is made redundant and the line is switched when a failure occurs. A 1 + 1 type or 1: N type redundant configuration that protects the communication is widely used. However, increasing the network cost due to the increase in the number of links is a problem in configuring a redundant path by these methods. Therefore, the adoption of a ring-type redundant communication path that enables redundancy with a small number of links is progressing.

  However, in a ring-type redundant communication path, when providing a multipoint-to-multipoint communication path such as wide area Ethernet (registered trademark), it is necessary to perform ring control that logically releases the loop and switches the path in the event of a failure. Become.

  Therefore, in the STP (Spanning Tree Protocol) described in Non-Patent Document 1 and the RSTP (Rapid Spanning Tree Protocol) described in Non-Patent Document 2, which are conventional ring control methods, a single port on a ring-type redundant communication path is used. The loop configuration is logically released by putting the in a blocking state. However, STP and RSTP handle various parameters for the calculation of the route cost for determining the network configuration. This increases the calculation cost for determining the route, and there is a problem that it takes time to switch.

Therefore, in MMRP2 described in Non-Patent Document 3, which is a conventional ring control method, a main device and a sub device are determined from a plurality of transfer devices constituting a ring-type redundant communication path, and the control port of the sub device is blocked. The logical loop is released, the control frame is transmitted / received between the main unit and the sub unit, and when the sub unit no longer receives the control frame from the main unit, the fault is detected, and the sub unit The path was switched by opening the control port that was blocked in In addition, by dividing the ring logically into frame identifiers such as VLAN (VirtualI Local Area Network), multiple logical rings are multiplexed on the ring-type redundant communication path to achieve efficient frame transfer. It was.
IEEE 802.1D-1998 Edition MAC bridges IEEE 802.1D-2004 Edition MAC bridges Masato Ando, “LAN Switch Technology -Redundancy and Latest Technology”, pp. 77-pp. 80, Internet week 2003 http: // www. nic. ad. jp / ja / materials / iw / 2003 / processedings / T14-2. pdf

  Here, in the conventional ring control method, when a failure is detected, the control port of the secondary device is opened without closing the control port of the main device, assuming that the loop is released at the failure location. As a result, when a control frame transmitted / received between the main device and the sub device is not received due to transfer delay or overflow of the transfer buffer in the device, it is erroneously detected as a failure even though no failure has actually occurred. However, opening the control port of the secondary device caused a loop.

  In addition, in a redundant route using a ring-type redundant communication path, a link to which a user frame is transferred during normal operation is a part of the link in the ring-type redundant communication path (hereinafter referred to as a main route), and the other links are standby links. Used only in case of failure. Therefore, the path switching is necessary only when a failure occurs in the main route, and the path switching is not necessary when the standby link fails. Further, the user frame does not need to be transferred to the standby link when it is normal.

  However, in the conventionally used ring control method, since it is impossible to identify a fault location, it is impossible to perform path switching control for each fault location. As a result, when a failure occurs in a standby link that does not require route switching, route switching is performed, which may cause the user's communication to become unstable or increase the frequency of occurrence of loops due to route switching failures. It was.

  Further, in the conventional ring control method, the control port can be set only for the main device and the sub device, and the user frame is transferred to all the links between the main device and the sub device. As described above, by transferring the user frame to the standby link that does not need to be transferred, the bandwidth of the multiplexed main path of the other logical ring is compressed, and the link usage efficiency is reduced.

  Further, in the conventional ring control method, it has been impossible to detect a failure of a control module that generates and transmits / receives a control frame. As a result, when a failure occurs in the control module, even if a user frame is received, the failure is detected by not receiving the control frame, and the path switching process is performed, causing a loop.

  Further, in the conventional ring control method, since there is no means for specifying the fault location, it is impossible to determine whether the fault is a single fault or a double fault. As a result, it is impossible to detect a double failure that cannot protect the user's communication even if the route is switched, and it is difficult for the administrator to grasp the situation of the failure.

  The present invention has been made in view of such problems, and an object of the present invention is to solve the problem that a loop occurs when a path is switched due to erroneous detection of a failure, and to transfer a user frame. The problem that cannot be restricted to the main route is solved, the problem that the unnecessary route switching is performed when a failure occurs in a link other than the main route, and the problem that the control function failure cannot be detected is solved. Another object of the present invention is to provide a ring-type redundant communication path control method that solves a problem that the situation cannot be grasped and cannot be controlled when a double failure occurs.

In order to solve the above-described problems, the present invention provides a ring-type redundant communication path constituted by a plurality of transfer devices, wherein the transfer device includes an inner port and an outer port, and the inner port is an outer port of another transfer device. A plurality of transfer devices including a main device having an open port as a control port, a sub device having a block port as a control port, and a control port. Control method for ring-type redundant communication path, which is distinguished from other devices that are not connected to each other, and each of which holds a device identifier and is given a device identifier string to which device identifiers are linked is sent and received using an inner port and an outer port The transfer device transmits a device identifier string of the inner loop control frame that is a control frame received from the inner loop port and the outer loop. A step of holding a device identifier string of an outer loop control frame, which is a control frame received from a port, in the identifier string storage unit; an own device identifier is added to the head of the device identifier string of the inner loop control frame; If there is, the step of deleting the own device identifier and transferring it to the outer port, adding the own device identifier to the head of the device identifier string of the outer control frame, and if the own device identifier exists at the end, the own device identifier If the local device identifier is included at the end of both the device identifier string of the inner loop control frame and the device identifier string of the outer loop control frame in the identifier string storage unit, the normal state is set. Detect and detect either the device identifier string of the inner loop control frame and / or the device identifier string of the outer loop control frame in the identifier string storage unit. If the transfer device is the main device when the failure is detected, it is detected that the device identifier is not included at the end of the Including a step of blocking the control port, giving an opening command to the inner control frame and the outer control frame and transferring them, and if the transfer device is a sub device, including a release command if the detected failure location is not the main device The control port is opened after receiving the inner loop control frame or the outer loop control frame, and if the detected failure location is the main device, the control port is immediately opened. Is a secondary device, the control port is blocked, and an opening command is given to the inner control frame and the outer control frame for transfer, and the transfer device is the main device. If there is, it includes a step of releasing the control port after receiving the inner control frame or the outer control frame including the release command.

  According to the present invention, in a ring-type redundant communication path constituted by a plurality of transfer devices, the transfer device includes an inner-circulation port and an outer-circulation port, and the inner-circulation port is connected to an outer-circulation port of another transfer device. Is connected to an inner port of another transfer device, and a plurality of transfer devices are distinguished between a main device having an open port as a control port, a sub device having a block port as a control port, and another device not having a control port. If the control frame is sent and received using the inward port and the outward port, each holds a device identifier and does not receive a control frame from the outer port for a certain period of time, a failure detection notification and its own device identifier are given to the control frame. If a control frame is not received from the inner port for a certain period of time, A method for controlling a ring-type redundant communication path in which a failure detection notification and its own device identifier are given to a network and transmitted from an outer port, and the transfer device transmits a control frame including the failure detection notification from the inner port or the outer port. When received, the step of detecting the occurrence of the failure and identifying the location of the failure, the device identifier string of the inner loop control frame that is the control frame received from the inner loop port, and the outer loop control that is the control frame received from the outer loop port A step of holding the device identifier sequence of the frame in the identifier sequence storage unit, a step of adding the own device identifier to the head of the device identifier sequence of the inner loop control frame and transferring it to the outer loop port, and a device identifier sequence of the outer loop control frame When the device identifier is added to the head and transferred to the inner port, and when a failure is detected If the transfer device is a main device, the control port is blocked, a step of transferring by giving an open command to the inner control frame and the outer control frame and transferring, and if the transfer device is a sub device, the detected fault location is If it is not the main device, the control port is released after receiving the inner control frame or the outer control frame including the release command, and if the detected fault is the main device, the step of immediately opening the control port and the failure When recovered, if the transfer device is a secondary device, the control port is closed, and a transfer command is given to the inner control frame and the outer control frame for transfer, and if the transfer device is the main device, the control port is opened. And a step of releasing the control port after receiving the inner control frame or the outer control frame including the command.

  In addition, the present invention provides a step of starting transmission of an inner loop control frame and an outer loop control frame by giving its own apparatus identifier and initial state notification when the transfer apparatus activates the control module, and from the inner loop port to the apparatus identifier string. When receiving a control frame including its own device identifier, the initial state notification of the inner loop control frame is deleted and transferred to the outer port, and a control frame including the own device identifier in the device identifier string is received from the outer port. In this case, it is preferable to include a step of deleting the initial state notification of the outer control frame and transferring it to the inner port, and a step of not detecting a failure when the control frame including the initial state notification is received.

  Further, the plurality of links of the ring-type redundant communication path are classified into a main path through which a user frame is transferred and another path that is a redundant link when a failure occurs, and the transfer device detects a failure. In this case, if the failure location is the main route and the transfer device that detected the failure is the main device, the control port is blocked, and an open command is given to the inner control frame and the outer control frame for transfer. If the transfer device that detected this is a secondary device, the control port is released after receiving the inner control frame or the outer control frame including the release command, and if the failure is not the main route, the control port is controlled. Preferably no steps are included.

  Also, if the transfer device does not receive the inner loop control frame for a certain period of time, it checks whether a user frame is received from the inner loop port, and if it does not receive the outer loop control frame for a certain period of time, whether it receives a user frame from the outer loop port Preferably, the method includes a step of detecting a failure of the control module if a user frame is received, and the transfer device stores device identifiers of all transfer devices connected to the ring redundant communication path. When there are a plurality of device identifiers that are not included in both the device identifier string of the inner loop control frame and the device identifier string of the outer loop control frame in the identifier string storage unit of the device identifiers of all transfer devices, it is detected as a double failure. Preferably, the method includes a step and a step of closing the control port when a double failure is detected.

  According to the present invention, it is possible for each transfer device to independently detect a failure and identify a failure occurrence location by performing failure detection and failure occurrence location identification using a device identifier string in a control frame. . If each transfer device controls independently, it becomes possible to set the control port to an arbitrary transfer device, suppress the transfer to the standby link that does not require the transfer of user frames, and other multiplexed logical rings. It becomes possible to increase the independence of the band used with the main route.

  When a failure is detected or recovery from a failure is detected, the transfer device that should open the control port waits for a release command from the transfer device that closed the control port, and performs the control port blocking process. When a failure occurs in the transfer device itself that should close the control port, the transfer device that should open the control port immediately closes the open control port by performing a release process on the control port. After confirmation, it is possible to take the procedure of opening the blocked control port, and control is performed so that a logical loop separation point always exists in a ring-type redundant communication path that is physically a loop. This makes it possible to prevent the occurrence of loops.

  In addition, if the failure location is not the main route, it is possible to keep the user's communication stable without performing unnecessary failure switching by not performing route switching. It is possible to suppress the frequency of occurrence.

  Further, by detecting the case of receiving a user frame without receiving a control frame as a control function failure, it is possible to prevent erroneous detection of a communication interruption of the user frame.

  Also, by distinguishing double faults from other single faults, it is possible to deal with double faults that cannot protect user communications even when the path is switched, and the administrator must understand the fault status. Becomes easy.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram of a ring-type communication path showing an application scene of the ring-type redundant communication path control method of the present invention. In the figure, an inward port 1A-1 of the transfer device 1A and an outer-circulation port 1D- of the transfer device 1D are shown. 2 is connected to the main path 2, the outer port 1B-2 of the transfer device 1B and the inner port 1C-1 of the transfer device 1C are connected to the sub route 3, and the outer port 1A-2 of the transfer device 1A and the transfer device 1B The inner circuit port 1B-1 is connected to the transfer path 4A, and the outer circuit port 1C-2 of the transfer apparatus 1C and the inner circuit port 1D-1 of the transfer apparatus 1D are connected to the transfer path 4B. Here, it is assumed that the main route device is the transfer device 1A and the transfer device 1D, and the sub route device is the transfer device 1B and the transfer device 1C.

  FIG. 2 is an internal configuration diagram of the transfer device 1 for carrying out the present invention. In the figure, the transfer device 1 includes an inner port 1-1 for transmitting / receiving a frame to / from an outer port of another transfer device. Holds the outer port 1-2 for sending / receiving frames to / from the inner port of another transfer device, and further holds the device state storage unit 11, the control frame operation unit 12, the frame transmission / reception unit 13, and the ring control unit 14. To do.

  The device state storage unit 11 has an “initial state”, “normal state”, “failure state”, “non-main path failure detection state”, “open command” as the device state, like the device state storage unit 11 of the storage unit configuration example shown in FIG. It retains the function of storing one of “standby state”, “double failure detection state”, and “control function failure state”.

  The frame transmission / reception unit 13 measures a reception interval between the control frame (inner control frame) received from the inner port 1-1 and the control frame (outer control frame) received from the outer port 1-2. Hold. The frame transmission / reception unit 13 receives a frame from the inner port 1-1 and the outer port 1-2, and measures a control frame and a user frame, and measures the reception interval of the inner control frame and the outer control frame. When the measurement interval time of the control frame counter unit 13-1 to be set exceeds a certain value, it is determined that no control frame is received, and the control frame operation unit 12 is notified of whether the control frame lost notification is inward or outward (circulation information). When the control frame is received from the control frame operation unit 12, the loop information of the control frame is extracted, and when the loop information is inward, the control frame is transmitted to the outer loop port. If it is, when sending a frame to the port , A function of transmitting a control frame in preference to a user frame, and a control function failure detected when a user frame is received without receiving a control frame, and a “control function failure state” is stored in the device state storage unit 11. And the function of memorizing.

  The control frame operation unit 12 holds an identifier string storage unit 12-1 and a notification information storage unit 12-2. The identifier string storage unit 12-1 has a function of managing the association of the device identifier string with the circulation information as shown in the identifier string storage unit 12-1 of FIG. The notification information storage unit 12-2 has a function of managing notification information in association with circulation information as shown in the notification information storage unit 12-2 of FIG.

  The control frame operation unit 12 extracts the circulation information and notification information from the control frame received from the frame transmission / reception unit 13, and stores the circulation information and the notification information in association with each other in the notification information storage unit 12-2. , A device identifier string is extracted from the control frame, the loop information and the device identifier string are stored in the identifier string storage unit 12-1 in association with each other, and the own device identifier is assigned to the head of the device identifier string If the device identifier is present at the end, the device identifier sequence for transmission is created by deleting the device identifier, and a control frame to which the device identifier sequence for transmission, the circulation information, and the notification information are added is created. When the control frame lost notification is received from the frame transmitting / receiving unit 13 and the function to create and transmit to the frame transmitting / receiving unit 13, the circulation information is extracted from the control frame lost notification and identified. Remove the device identifier string related peripheral times information from the sequence memory 12-1, retains the ability to remove the notification information regarding the circumferential times information from the notification information storage section 12-2.

  The ring control unit 14 includes a failure inspection unit 14-1, a ring setting storage unit 14-2, a failure switching processing unit 14-3, a failure recovery processing unit 14-4, and a port control unit 14-5. To do.

  The failure checking unit 14-1 has a function of checking a failure from the information in the identifier string storage unit 12-1 of the control frame operation unit 12 according to the flowchart shown in FIG. As shown in the ring setting storage unit 14-2 in FIG. 3, the ring setting storage unit 14-2 uses the identifiers of all transfer devices connected to the ring redundant communication path as “device identifiers”, and The type (main device / sub device / other device) is set as “device type”, the device identifier of the main route device is set as “main route device”, and the device identifier of the sub route device is set as “sub route device”. When the device is not a device, a function of storing the device identifier of the main device as “main device” and the control port of the own device as “control port” is retained. The port control unit 14-5 has a function of closing or opening the control port.

  When the device state stored in the device state storage unit 11 is normal, the ring control unit 14 detects a failure in the failure inspection unit 14-1, and the failure point is a main route device or a main route. If there is a failure state, a failure switching processing unit 14-3 (to be described later) performs failure switching processing. If the device state stored in the device state storage unit 11 is a failure state, the failure inspection unit 14-1 In the case where no failure is detected, the failure recovery processing unit 14-4, which will be described later, performs a recovery process, and the device state stored in the device state storage unit 11 is an open command standby state or a double failure detection state In this case, when the failure inspection unit 14-1 detects a failure, a failure switching processing unit 14-3 described later performs a failure switching process, and the failure inspection unit 14-1 does not detect the failure. The failure recovery process described later 14-4 is a function for performing failure recovery processing, and when the failure is detected by the failure inspection unit 14-1 when the device state stored in the device state storage unit 11 is the initial state, failure switching processing is performed. Retain functions that are not performed.

  The failure switching processing unit 14-3 stores the release command in the notification information storage unit 12-2 of the control frame operation unit 12 when the own device type stored in the ring setting storage unit 14-2 is the main device. The port control unit 14-5 is instructed to close the control port, the failure state is stored in the device state storage unit 11, and the own device type stored in the ring setting storage unit 14-2 is the sub device. In a case where the main device identifier stored in the ring setting storage unit 14-2 is a device identifier detected as a failure by the failure inspection unit 14-1, the port control unit 14-5 The control port is instructed to be opened, the failure state is stored in the device state storage unit 11, and the main device identifier stored in the ring setting storage unit 14-2 is indicated as a failure in the failure inspection unit 14-1. Detected device identification If it was not a child retains the function of storing the open command standby state to the device state storage unit 11.

  When the own device type stored in the ring setting storage unit 14-2 is the main device, the failure recovery processing unit 14-4 stores the release command standby state in the device state storage unit 11, and the ring setting storage unit When the own device type stored in 14-2 is a secondary device, the release command is stored in the notification information storage unit 12-2 of the control frame operation unit 12, and the port control unit 14-5 is informed of the control port. A function of instructing blockage and storing the normal state in the apparatus state storage unit 11 is retained.

  Next, the operation of the present invention will be described. FIG. 5 is a diagram showing an embodiment of a ring communication channel system to which the ring redundant communication channel control method of the present invention is applied. In FIG. 5, the inner circuit of the transfer device 1A whose device identifier is “A” The port 1A-1 and the external port 1D-2 of the transfer device 1D whose device identifier is “D” are connected to the main path 2, and the external port 1B-2 and the device identifier of the transfer device 1B whose device identifier is “B” The inward port 1C-1 of the transfer device 1C with "C" is connected to the sub route 3, the outer route port 1A-2 of the transfer device 1A and the inner port 1B-1 of the transfer device 1B are connected to the crossing route 4A, An outer port 1C-2 of the transfer device 1C and an inner port 1D-1 of the transfer device 1D are connected to the transfer path 4B.

  Here, the main device is the transfer device 1A (hereinafter referred to as main device A), the sub device is the transfer device 1B (hereinafter referred to as sub device B), and the inner port 1A-1 and the outer port 1B-2 are control ports. To do. Further, assume that the main path device is the transfer device 1A and the transfer device 1D, and the sub route device is the transfer device 1B and the transfer device 1C.

  Further, the control frame transmitted / received between the transfer devices by the creation of the control frame by the control frame operation unit 12 of each transfer device includes a device identifier string as shown in FIG. In the device identifier string of the control frame shown in FIG. 5, the traveling direction of the control frame is the head, and the opposite side to the traveling direction is the tail.

  FIG. 6 shows an example of the ring setting storage unit 14-2A of the main device A and the ring setting storage unit 14-2B of the sub device B. The ring setting storage unit 14-2A of the main device A includes a device identifier. “A, B, C, D” as the device type, “main device” as the device type, “A, D” as the main route device, “B, C” as the sub route device, and the own device as the main device. Therefore, “NULL” is stored as the main device, “1A-1” is stored as the control port, and “A, B, C, D” is stored as the device identifier in the ring setting storage unit 14-2B of the secondary device B. “Sub-device” as type, “A, D” as main route device, “B, C” as sub-route device, “A” as main device, and “1B-2” as control port are stored. Yes.

  FIG. 7 shows an example of the device state storage unit 11, the identifier string storage unit 12-1, and the notification information storage unit 12-2 of the main device A and the sub device B in the normal state. “Normal state” is stored in the device state storage unit 11B of the unit 11A and the secondary device B, and the device identifier string “DCBA” is stored in the identifier column storage unit 12-1A of the main device A with respect to the circulation information “inner circuit”. ”Is stored in the device identifier string“ BCDA ”for the circulation information“ outward ”, and the device identifier string“ ADCB ”is stored in the identifier string storage unit 12-1B of the sub-device B for the circulation information“ inner ”. , The device identifier string “CDAB” is stored for the circulation information “outward”, and the circulation information “inner” is stored in the notification information storage unit 12-2A of the main device A and the notification information storage unit 12-2B of the secondary device B. "NULL" is stored for both "outside" .

  FIG. 8 is an explanatory diagram showing a case where a failure has occurred in the main route 2. The main apparatus A stops receiving a frame from the inward port 1A-1, and the frame transmission / reception unit 13 detects that the control frame counter unit 13-1 does not receive an inward control frame for a certain period of time. 12, the inward control frame lost notification is performed, and the outer control frame received from the outer control port 1A-2 is transferred to the control frame operation unit 12.

  Upon receiving the control frame lost notification, the control frame operation unit 12 deletes the device identifier sequence of the entry whose circulation information is “inner loop” as shown in the identifier sequence storage unit 12-1A of the main device A in FIG. Store “NULL”. Further, the device identifier string “BCD” is extracted from the outer loop control frame, and “BCD” is stored in the device identifier string of the entry whose circulation information of the identifier string storage unit 12-1A is “outer loop”. Further, the device identifier string is set to “A” as the inner loop control frame, and the device identifier string is set to “ABCD” as the outer loop control frame, and transferred to the frame transmitting / receiving unit 13.

  The frame transmission / reception unit 13 of the main apparatus A transmits the inner loop control frame received from the control frame operation unit 12 to the outer loop port 1A-2, and transmits the outer loop control frame to the inner loop port 1A-1.

  The failure checking unit 14-1 of the ring control unit 14 of the main device A checks the entry in the identifier string storage unit 12-1A, and detects a link failure between the own device and the transfer device 1D from the flowchart of FIG. Detect.

  The ring control unit 14 of the main device A determines that the failure location is between the main route devices A and D stored in the ring setting storage unit 14-2A, and sends a failure switching command to the failure switching processing unit 14-3. I do.

  In the failure switching processing unit 14-3 of the main device A, since the device type stored in the ring setting storage unit 14-2A is “main device”, the ring setting storage unit 14- The block command for the control port 1A-1 stored in 2A is issued.

  The port control unit 14-5 that has received the block command blocks the control port 1A-1 according to the block command of the control port 1A-1.

  The failure switching processing unit 14-3 of the main device A stores an “release command” in the notification information as shown in the notification information storage unit 12-2A of the main device A of FIG. 9, and the device of the main device A of FIG. As shown in the state storage unit 11A-1, the “failure state” is stored in the apparatus state storage unit.

  In the control frame operation unit 12 of the main device A, the device identifier string is “A” as the inner loop control frame, the notification information is “release command”, the device identifier string is “ABCD” as the outer loop control frame, and the notification information is “release command”. ”And forward to the frame transmitting / receiving unit 13.

  The frame transmission / reception unit 13 of the main apparatus A transmits the inner loop control frame received from the control frame operation unit 12 to the outer loop port 1A-2, and transmits the outer loop control frame to the inner loop port 1A-1.

  In the secondary device B, the frame transmitting / receiving unit 13 transfers the inner loop control frame received from the inner loop port 1B-1 and the outer loop control frame received from the outer loop port 1B-2 to the control frame operation unit 12.

  In the control frame operation unit 12 of the secondary device B, the device identifier “A” is extracted from the inner loop control frame, the device identifier string “CD” is extracted from the outer loop control frame, and the identifier string storage unit 12 of the secondary device B in FIG. As shown in -1B, “A” is stored in the device identifier column of the entry whose circulation information is “inner circuit”, and “CD” is stored in the device identifier column of the entry of “outer circuit”. Further, the device identifier string is set to “BA” as the inner loop control frame, and the device identifier string is set to “BCD” as the outer loop control frame, and transferred to the frame transmitting / receiving unit 13.

  The frame transmission / reception unit 13 of the secondary device B transmits the inner loop control frame received from the control frame operation unit 12 to the outer loop port 1B-2, and transmits the outer loop control frame to the inner loop port 1B-1.

  The failure check unit 14-1 of the ring control unit 14 of the secondary device B checks the entry in the identifier string storage unit 12-1B, and the link failure between the transfer device 1A and the transfer device 1D from the flowchart of FIG. Is detected.

  The ring control unit 14 of the secondary device B determines that the failure location is between the main route devices A and D stored in the ring setting storage unit 14-2B, and sends a failure switching command to the failure switching processing unit 14-3. I do.

  In the failure switching processing unit 14-3 of the secondary device B, since the device type stored in the ring setting storage unit 14-2B is “secondary device”, the main device stored in the ring setting storage unit 14-2B It is confirmed that “A” is alive, and “open command waiting state” is stored in the device state as shown in the device state storage unit 11B-1 of the secondary device B in FIG.

  When the secondary device B receives the control frame to which the “release command” is given in the main device A as described above, in the secondary device B, the frame transmission / reception unit 13 receives the inner loop control frame received from the inner loop port 1B-1. Then, the outer-circumference control frame received from the outer-circulation port 1B-2 is transferred to the control frame operation unit 12, and the control frame operation unit 12 extracts the notification information “release command” from the inner-circumference control frame, and the notification information from the outer-circulation control frame. The “release command” is extracted, and the “release command” is stored in the notification information as shown in the notification information storage unit 12-2B of the secondary device B in FIG.

  In the ring control unit 14 of the secondary device B, when “open command standby state” is stored in the device state as shown in the device state storage unit 11B-1 of the secondary device B in FIG. Referring to the section 12-2B, when “open command” is stored in the notification information as shown in the notification information storage section 12-2B of the secondary device B in FIG. The command is issued, and the “failure state” is stored in the device state as shown in the device state storage unit 11B-2 of the secondary device B in FIG.

  In the failure switching processing unit 14-3 that has received the failure switching command, the port switching unit 14-5 issues a command to open the control port 1B-2 stored in the ring setting storage unit 14-2.

  The port control unit 14-5 that has received the release command opens the control port 1B-2 in accordance with the release command for the control port 1B-2.

  With the above operation, the open port is closed after the failure is switched, and then the closed port is opened. Therefore, it is possible to prevent the occurrence of a loop when a failure is erroneously detected. Further, by following the failure detection flow of FIG. 4, it is possible to detect both bidirectional link breaks and unidirectional link breaks. Further, in the transfer apparatuses 1C and 1D, processing as a sub apparatus is performed in the same manner as the sub apparatus B, so that control ports can be set for a plurality of transfer apparatuses.

  Next, a case where the above-described failure in the main route 2 is recovered will be described. In the main device A or the sub device B, the failure inspection unit 14-1 periodically performs a failure inspection according to the flowchart of FIG. 4, and stores the “failure state” as shown in the device state storage unit 11A-1 of FIG. If a failure is not detected by the failure inspection by the failure inspection unit 14-1, a failure recovery command is issued to the failure recovery processing unit 14-4.

  In the main apparatus A, since the apparatus type stored in the ring setting storage section 14-2A is the “main apparatus”, the failure recovery processing section 14-4 that has received the failure recovery instruction is the apparatus status storage in FIG. As shown in the section 11A-2, the “open command waiting state” is stored.

  In the secondary device B, the failure recovery processing unit 14-4 that has received the failure recovery command has the device type stored in the ring setting storage unit 14-2B as “secondary device”, so the port control unit 14-5. In response to this, the closing command for the control port 1B-2 stored in the ring setting storage unit 14-2 is issued.

  The port control unit 14-5 that has received the block command blocks the control port 1B-2 in accordance with the block command for the control port 1B-2.

  In the failure switching processing unit 14-3 of the secondary device B, the “release command” is stored in the notification information as shown in the notification information storage unit 12-2B in FIG. 9, and is shown in the device state storage unit 11B-3 in FIG. Thus, the “normal state” is stored in the apparatus state.

  In the control frame operation unit 12 of the sub-device B, an inner loop control frame and an outer loop control frame are created by giving an “release command” stored in the notification information of the notification information storage unit 12-2 in FIG. Transfer to the transceiver 13.

  The frame transmission / reception unit 13 of the secondary device B transmits the inner loop control frame received from the control frame operation unit 12 to the outer loop port 1B-2, and transmits the outer loop control frame to the inner loop port 1B-1.

  In the main apparatus A, the frame transmission / reception unit 13 transfers the inner loop control frame received from the inner loop port 1A-1 and the outer loop control frame received from the outer loop port 1A-2 to the control frame operation unit 12.

  When the main apparatus A receives the control frame to which the “release command” is given in the sub apparatus B as described above, in the main apparatus A, the frame transmission / reception unit 13 receives the inner loop control frame received from the inner port 1A-1. Then, the outer-circumference control frame received from the outer-circulation port 1A-2 is transferred to the control frame operation unit 12, and the control frame operation unit 12 extracts the notification information “release command” from the inner-circumference control frame, and the notification information from the outer-circulation control frame. “Open command” is extracted, and “open command” is stored in the notification information as shown in the notification information storage unit 12-2A in FIG.

  In the ring control unit 14 of the main device A, when the “open command standby state” is stored in the device state storage unit 11A-2, the notification information storage unit 12-2A is periodically referred to and the notification information of FIG. As shown in the storage unit 12-2A, when the “release command” is stored in the notification information, a failure recovery command is issued to the failure recovery processing unit 14-4, as shown in the apparatus state storage unit 11A-3 of FIG. Stores “normal state” in the device state.

  In the failure recovery processing unit 14-4 that has received the failure recovery command, the port control unit 14-5 is instructed to release the control port 1A-1 stored in the ring setting storage unit 14-2.

  The port control unit 14-5 that has received the release command opens the control port 1A-1 in accordance with the release command for the control port 1A-1.

  With the above operation, even when the fault location is recovered, the closed port is opened after the open port is closed, so that the occurrence of a loop can be prevented.

  FIG. 10 is an explanatory diagram showing a case where a failure has occurred in the main apparatus A. The sub-device B stops receiving frames from the inward port 1B-1, and the frame transmission / reception unit 13 detects that the control frame counter unit 13-1 does not receive the inner control frame for a certain period of time. 12, the inward control frame lost notification is performed, and the outer control frame received from the outer control port 1B-2 is transferred to the control frame operation unit 12.

  Upon receiving the control frame lost notification, the control frame operation unit 12 deletes the device identifier sequence of the entry whose circulation information is “inside” as shown in the identifier sequence storage unit 12-1B of FIG. 11, and sets “NULL”. Remember. Further, the device identifier string “CD” is extracted from the outer loop control frame, and “CD” is stored in the device identifier string of the entry whose circulation information is “outer loop” as shown in the identifier string storage unit 12-1B of FIG. . Further, the device identifier string is set to “B” as the inner loop control frame, the device identifier string is set to “BCD” as the outer loop control frame, and transferred to the frame transmitting / receiving unit 13.

  The frame transmission / reception unit 13 of the secondary device B transmits the inner loop control frame received from the control frame operation unit 12 to the outer loop port 1B-2, and transmits the outer loop control frame to the inner loop port 1B-1.

  The failure checking unit 14-1 of the ring control unit 14 of the secondary device B checks the entry in the identifier string storage unit and detects the device failure of the transfer device 1A from the flowchart of FIG.

  The ring control unit 14 of the secondary device B determines that the transfer device 1A detected as the failure location is the main device A stored in the ring setting storage unit 14-2B, and causes the failure switching processing unit 14-3 to Perform a switching command.

  In the failure switching processing unit 14-3 of the secondary device B, the device type stored in the ring setting storage unit 14-2B is “secondary device”, and the main device “ Since “A” is a faulty device, the port control unit 14-5 is instructed to release the control port 1B-2 stored in the ring setting storage unit 14-2B, and is shown in the device state storage unit 11B of FIG. Thus, the “failure state” is stored in the device state.

  The port control unit 14-5 that has received the release command opens the control port 1B-2 in accordance with the release command for the control port 1B-2.

  With the above operation, if a failure occurs in the main unit during failure switching, the blocked port is opened without waiting for the reception of the release command from the main unit, so failure switching is performed even when the main unit fails. Is possible.

  FIG. 12 is an explanatory diagram showing a case where a failure has occurred in the transfer route 4B. In the main apparatus A, the frame transmission / reception unit 13 transfers the inner loop control frame received from the inner loop port 1A-1 and the outer loop control frame received from the outer loop port 1A-2 to the control frame operation unit 12.

  The control frame operation unit 12 of the main device A extracts the device identifier “D” from the inner loop control frame, extracts the device identifier string “BC” from the outer loop control frame, and stores it in the device identifier string storage unit 12-1A of FIG. As shown, “D” is stored in the device identifier of the entry whose circulation information is “inside”, and “BC” is stored in the device identifier column of the entry whose circulation information is “outside”. Further, the device identifier string is set to “AD” as the inner loop control frame, and the device identifier string is set to “ABC” as the outer loop control frame, and transferred to the frame transmitting / receiving unit 13.

  The frame transmission / reception unit 13 of the main apparatus A transmits the inner loop control frame received from the control frame operation unit 12 to the outer loop port 1A-2, and transmits the outer loop control frame to the inner loop port 1A-1.

  The failure check unit 14-1 of the ring control unit 14 of the main device A checks the entry in the identifier string storage unit and detects a link failure between the transfer device 1C and the transfer device 1D from the flowchart of FIG. .

  The ring control unit 14 of the main device A determines that the failure location is not between the main route devices A and D stored in the ring setting storage unit 14-2A, as shown in the device state storage unit 11A of FIG. Stores “non-main-path failure detection state” in the device state.

  In the secondary device B, the frame transmitting / receiving unit 13 transfers the inner loop control frame received from the inner loop port 1B-1 and the outer loop control frame received from the outer loop port 1B-2 to the control frame operation unit 12.

  In the control frame operation unit 12 of the secondary device B, the device identifier string “AD” is extracted from the inner loop control frame, and the device identifier “C” is extracted from the outer loop control frame, which is shown in the identifier string storage unit 12-1B in FIG. Thus, “AD” is stored in the device identifier column of the entry whose circulation information is “inner”, and “C” is stored in the device identifier column of the entry of “outer”. Further, the device identifier string is set to “BAD” as the inner loop control frame, the device identifier string is set to “BC” as the outer loop control frame, and transferred to the frame transmitting / receiving unit 13.

  The frame transmission / reception unit 13 of the secondary device B transmits the inner loop control frame received from the control frame operation unit 12 to the outer loop port 1B-2, and transmits the outer loop control frame to the inner loop port 1B-1.

  The failure inspection unit 14-1 of the ring control unit 14 of the secondary device B determines that the failure location is not between the main route devices A and D stored in the ring setting storage unit 14-2B, and the device of FIG. As shown in the state storage unit 11B, “non-main path failure detection state” is stored in the apparatus state.

  With the above operation, when a failure occurs on a route other than the main route, failure switching is not performed even if a failure is detected.

  Next, the operation in the initial state when the transfer device is activated or when the control function is activated will be described. The main apparatus A stores “initial state” in the apparatus state as shown in the apparatus state storage unit 11A of FIG.

  In the control frame operation unit 12 of the main device A, “NULL” is stored as the device identifier string as shown in the identifier string storage unit 12-1A-1 in FIG. 14, and the notification information storage unit 12-2A-1 in FIG. As shown in FIG. 4, “initial state” is stored as notification information.

  In the control frame operation unit 12 of the main device A, “A” is assigned as the device identifier string, and “initial state” stored in the notification information storage unit 12-2A-1 in FIG. A frame and an outer loop control frame are created and transferred to the frame transmitting / receiving unit 13.

  The frame transmission / reception unit 13 of the main apparatus A transmits the inner loop control frame received from the control frame operation unit 12 to the outer loop port 1A-2, and transmits the outer loop control frame to the inner loop port 1A-1.

  In the secondary device B, the frame transmitting / receiving unit 13 transfers the inner loop control frame received from the inner loop port 1B-1 and the outer loop control frame received from the outer loop port 1B-2 to the control frame operation unit 12.

  In the control frame operation unit 12 of the secondary device B, the device identifier “A” and the notification information “initial state” are extracted from the inner loop control frame, the device identifier string “CD” is extracted from the outer loop control frame, and the identifier shown in FIG. As shown in the column storage unit 12-1B, “A” is stored in the device identifier column of the entry whose circulation information is “inner circuit”, and “CD” is stored in the device identifier column of the entry of “outer circuit”. As shown in the notification information storage unit 12-2B, the “initial state” is stored in the notification information of the entry whose circulation information is “inner circle”. Further, the device identifier string is set to “BA” as the inner loop control frame, and the device identifier string is set to “BCD” as the outer loop control frame, and transferred to the frame transmitting / receiving unit 13.

  The frame transmission / reception unit 13 of the secondary device B transmits the inner loop control frame received from the control frame operation unit 12 to the outer loop port 1B-2, and transmits the outer loop control frame to the inner loop port 1B-1.

  In the failure inspection unit 14-1 of the ring control unit 14 of the secondary device B, the “initial state” is stored in the notification information storage unit 12-2B, and therefore no failure detection is performed.

  When the control frame is transferred in the transfer apparatuses 1C and 1D as described above, the main apparatus A receives “DCBA” as the apparatus identifier string of the inner loop control frame and “BCDA” as the apparatus identifier string of the outer loop control frame. In the control frame operation unit 12 of A, as shown in the identifier sequence storage unit 12-1A-2 in FIG. 14, “DCBA” is entered in the device identifier sequence of the entry whose circulation information is “inner”, and the entry is “outer”. 14 is stored in the device identifier string of FIG. 14 and the device identifier string “A” is included at the end of the device identifier string of the inner loop control frame and the device identifier string of the outer loop control frame. “NULL” is stored in the notification information of 12-2A-2.

  With the above operation, it is possible to prevent the device identifier string from being detected as a failure before it converges to the initial state.

  FIG. 15 is an explanatory diagram showing a case where a double failure has occurred in the main route 2 and the sub route 3. The main apparatus A stops receiving a frame from the inward port 1A-1, and the frame transmission / reception unit 13 detects that the control frame counter unit 13-1 does not receive an inward control frame for a certain period of time. 12, the inward control frame lost notification is performed, and the outer control frame received from the outer control port 1A-2 is transferred to the control frame operation unit 12.

  Upon receiving the control frame lost notification, the control frame operation unit 12 deletes the device identifier sequence of the entry whose circulation information is “inside” as shown in the identifier sequence storage unit 12-1A of FIG. 16, and sets “NULL”. Remember. Further, the device identifier string “B” is extracted from the outer loop control frame, and “B” is stored in the device identifier string of the entry whose circulation information in the identifier string storage unit 12-1A is “outer loop”. Further, the device identifier string is set to “A” as the inner loop control frame, and the device identifier string is set to “AB” as the outer loop control frame, and transferred to the frame transmitting / receiving unit 13.

  The frame transmission / reception unit 13 of the main apparatus A transmits the inner loop control frame received from the control frame operation unit 12 to the outer loop port 1A-2, and transmits the outer loop control frame to the inner loop port 1A-1.

  In the fault check unit 14-1 of the ring control unit 14 of the main device A, the entry in the identifier string storage unit 12-1A is checked, and the device identifier string and the turn information of the entry whose turn information is “inner turn” are “outer turn”. ”Does not include a plurality of device identifiers C and D. Therefore, a double failure is detected from the flow chart of FIG. 4 and the device status is set to“ “Double failure detection status” is stored.

  The sub-device B stops receiving the frame from the outer-circulation port 1B-2, and the frame transmission / reception unit 13 detects that the control frame counter unit 13-1 does not receive the outer-circulation control frame for a certain period of time. 12, the outer control frame lost notification is performed, and the inner control frame received from the inner port 1B-1 is transferred to the control frame operation unit 12.

  Upon receiving the control frame lost notification, the control frame operation unit 12 deletes the device identifier string of the entry whose circulation information is “external” as shown in the identifier string storage unit 12-1B of FIG. 16, and sets “NULL”. Remember. Further, the device identifier string “A” is extracted from the inner loop control frame, and “A” is stored in the device identifier string of the entry whose circulation information in the identifier string storage unit 12-1B is “inner loop”. Further, the device identifier string is set to “BA” as the inner loop control frame, and the device identifier string is set to “B” as the outer loop control frame, and transferred to the frame transmitting / receiving unit 13.

  The frame transmission / reception unit 13 of the secondary device B transmits the inner loop control frame received from the control frame operation unit 12 to the outer loop port 1B-2, and transmits the outer loop control frame to the inner loop port 1B-1.

  The fault checking unit 14-1 of the ring control unit 14 of the secondary device B checks the entry in the identifier string storage unit 12-1B, detects a double fault from the flowchart of FIG. 4, and stores the device status storage of FIG. As shown in the section, “double failure detection state” is stored in the apparatus state.

  With the above operation, when a double failure occurs, it is possible to detect the failure as a double failure and not switch over the failure.

  FIG. 17 shows that the control function of the main device A has failed and the inner port 1B-1 of the sub device B and the outer port 1D-2 of the transfer device 1D receive the user frame from the main device A, but the control frame It is explanatory drawing which showed the case where it stops receiving.

  In the secondary device B, the control frame is not received from the inward port 1B-1, and in the frame transmitting / receiving unit 13, the control frame counter unit 13-1 does not receive the inward control frame for a certain period of time. In addition, since a user frame that is not a control frame is received, it is detected that there is a failure in the control function of the adjacent transfer device, and as shown in the device state storage unit 11B in FIG. "Functional failure state" is stored.

  As a result of the above operation, when a failure occurs in the control function, it is detected as a failure in the control function in another device, and the occurrence of a loop can be prevented without switching the failure.

  In the embodiment of the present invention, the number of transfer devices is four and the number of sub-devices is one, but there is no limitation on the number of each.

  Also, when a control frame is sent and received with a device identifier string always attached, but a failure is detected by not receiving a control frame from an adjacent transfer device, a failure detection flag and device identifier are added to the control frame. Thus, the transfer device that has received the control frame to which the failure detection flag is attached can detect the failure even by updating and transferring the device identifier string.

  In addition, between the main apparatus and the sub apparatus, it is possible to detect a failure and switch a path by a method of transmitting and receiving a control frame only when a failure is detected without transmitting and receiving a control frame in a normal state. It is also possible to logically multiplex a ring redundant communication path with an identifier such as VLAN.

  Other forms are not necessarily limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention, and the object of the present invention can be achieved and the following effects can be achieved. Of course, it can be implemented with appropriate modifications.

  The first effect of the present invention is that switching can be performed without causing a loop when switching a fault. In addition, it is possible to prevent the occurrence of a loop even if the failure is switched when a failure is erroneously detected. The reason for this is to open the blocked port after confirming that the opened control port is blocked at the time of failure switching.

  The second effect of the present invention is that it is possible to perform a failure switching process according to a failure location and prevent unnecessary switching. The reason is that the failure location and the failure type (one-way / two-way) are detected using a control frame between links.

  The third effect of the present invention is that the control port can be set to an arbitrary port of an arbitrary transfer device, and a link for transferring a frame on the ring-type redundant communication path can be limited. The reason is that by including a device identifier string in the inter-link control frame, each transfer device independently detects a failure and identifies a failure location, and each transfer device independently performs a switching process.

  According to the fourth effect of the present invention, it is possible to prevent the occurrence of a loop due to the failure switching because the failure of the control function is detected and is not erroneously detected as the failure of the user frame. The reason is to check whether a user frame is received when a control frame is not received.

It is a system diagram of a ring type communication path showing an application scene of the ring type redundant communication path control method of the present invention. It is an internal block diagram of the transfer apparatus for implementing this invention. It is a figure which shows the memory | storage part structural example for implementing this invention. It is a flowchart which detects a failure. It is a figure which shows one Embodiment of the ring type channel system to which the ring type redundant channel control method of this invention is applied. It is a figure which shows a ring setting memory | storage part example. It is a figure which shows the example of a memory | storage part at the time of normal. It is explanatory drawing which showed the case where a failure generate | occur | produced in the main path | route. It is a figure which shows the example of a memory | storage part at the time of the main path | route failure and recovery. It is explanatory drawing which showed the case where a failure generate | occur | produced in the main apparatus. It is a figure which shows the example of a memory | storage part at the time of the main apparatus failure. It is explanatory drawing which showed the case where a failure generate | occur | produced in the transfer route It is a figure which shows the example of a memory | storage part at the time of a transfer route failure. It is a figure which shows the memory | storage part example of an initial state. It is explanatory drawing which showed the case where a double failure generate | occur | produced. It is a figure which shows the memory | storage part example at the time of a double failure. It is explanatory drawing when a control function failure generate | occur | produces. It is a figure which shows the example of a memory | storage part at the time of a control function failure.

Explanation of symbols

1, 1A, 1B, 1C, 1D Transfer device 1-1, 1A-1, 1B-1, 1C-1, 1D-1 Inner port 1-2, 1A-2, 1B-2, 1C-2, 1D- 2 Outer port 2 Main route 3 Sub route 4A, 4B Crossing route 11 Device state storage unit 12 Control frame operation unit 12-1 Identifier string storage unit 12-2 Notification information storage unit 13 Frame transmission / reception unit 13-1 Control frame counter unit 14 Ring control unit 14-1 Fault inspection unit 14-2 Ring setting storage unit 14-3 Fault switching processing unit 14-4 Fault recovery processing unit 14-5 Port control unit

Claims (6)

In a ring-type redundant communication path constituted by a plurality of transfer devices, the transfer device includes an inner port and an outer port, the inner port is connected to an outer port of another transfer device, and the outer port is another transfer device. A plurality of transfer devices are distinguished from a main device having an open port as a control port, a sub device having a block port as a control port, and another device not having a control port, and a device identifier. And a control method for a ring-type redundant communication path that transmits and receives a control frame to which a device identifier string obtained by concatenating device identifiers is transmitted and received using an inner port and an outer port,
The transfer device is
Holding the device identifier string of the inner loop control frame that is a control frame received from the inner loop port and the device identifier string of the outer loop control frame that is a control frame received from the outer loop port in the identifier string storage unit;
Adding the own device identifier to the head of the device identifier string of the inner loop control frame, deleting the own device identifier if it exists at the end, and transferring it to the outer port;
Adding the own device identifier to the head of the device identifier string of the outer loop control frame and deleting the own device identifier if it exists at the end and transferring it to the inner port;
If the own device identifier is included at the end of both the device identifier string of the inner loop control frame and the device identifier string of the outer loop control frame of the identifier string storage unit, a normal state is detected and the inner loop control of the identifier string storage unit A step of detecting the occurrence of a failure when the own device identifier is not included at the end of either or both of the device identifier sequence of the frame and the device identifier sequence of the outer control frame, and identifying the location where the failure has occurred Including
When a failure is detected,
If the transfer device is a main device, the control port is closed, and a transfer instruction is given to the inner control frame and the outer control frame for transfer, and transferred.
If the transfer device is a secondary device, if the detected failure location is not the main device, the control port is opened after receiving the inner control frame or the outer control frame including the release command, and the detected failure location is the main device. And immediately opening the control port,
When a failure is recovered,
If the transfer device is a secondary device, the control port is closed, and a transfer instruction is given to the inner control frame and the outer control frame for transfer, and transferred.
If the transfer device is a main device, the method includes a step of releasing a control port after receiving an inner loop control frame or an outer loop control frame including a release command. In a ring-type redundant communication path constituted by a plurality of transfer devices, the transfer device includes an inner port and an outer port, the inner port is connected to an outer port of another transfer device, and the outer port is connected to the other transfer device. A plurality of transfer devices connected to the inner port are distinguished from a main device having an open port as a control port, a sub device having a blocked port as a control port, and another device not having a control port. When the control frame is transmitted / received using the outer-circulation port, the device identifier is held, and when the control frame is not received from the outer-circulation port for a certain period of time, the failure detection notification and the own device identifier are given to the control frame, If it does not receive a control frame from the inner port for a certain period of time, A method of controlling a ring redundant communication path to be transmitted from the outer loop port to impart harm detection notification and the own device identifier,
The transfer device is
Detecting a fault occurrence when a control frame including a fault detection notification is received from an inner port or an outer port, and identifying the location of the fault;
Holding the device identifier string of the inner loop control frame that is a control frame received from the inner loop port and the device identifier string of the outer loop control frame that is a control frame received from the outer loop port in the identifier string storage unit;
Adding the own device identifier to the head of the device identifier string of the inner loop control frame and transferring it to the outer loop port;
Adding the own device identifier to the head of the device identifier string of the outer loop control frame and transferring it to the inner loop port;
When a failure is detected,
If the transfer device is a main device, the control port is closed, and a transfer instruction is given to the inner control frame and the outer control frame for transfer, and transferred.
If the transfer device is a secondary device, if the detected failure location is not the main device, the control port is opened after receiving the inner control frame or the outer control frame including the release command, and the detected failure location is the main device. If so, immediately open the control port;
When a failure is recovered,
If the transfer device is a secondary device, the control port is closed, and a transfer instruction is given to the inner control frame and the outer control frame for transfer, and transferred.
If the transfer device is a main device, the method includes a step of releasing a control port after receiving an inner loop control frame or an outer loop control frame including a release command. In the ring type redundant channel control method according to claim 1,
The transfer device is
When the control module is activated, a step of giving an own device identifier and an initial state notification and starting transmission of an inner loop control frame and an outer loop control frame;
A step of deleting an initial state notification of the inner control frame and transferring it to the outer port when receiving a control frame including the device identifier in the device identifier string from the inner port;
When receiving a control frame including its own device identifier in the device identifier string from the outer loop port, deleting the initial state notification of the outer loop control frame and transferring it to the inner port;
A ring redundant communication path control method, comprising: a step of not detecting a failure when a control frame including an initial state notification is received. In the ring-type redundant communication path control method according to any one of claims 1 to 3,
Differentiate the multiple links of the ring-type redundant communication path into a main path through which user frames are transferred and other paths that are redundant links when a failure occurs.
When the transfer device detects a failure, if the failure occurrence location is the main route and the transfer device that detected the failure is the main device, the control port is blocked, and an open command is sent to the inner control frame and the outer control frame. If the transfer device that detected the failure is the secondary device, the control port is opened after receiving the inner control frame or the outer control frame including the release command, and the location of the failure must be on the main route. For example, a ring type redundant communication path control method including a step of not performing control of the control port. In the ring-type redundant communication path control method according to any one of claims 1 to 4,
If the transfer device does not receive an inner loop control frame for a certain period of time, it checks whether a user frame is received from the inner loop port, and if it does not receive an outer loop control frame for a certain period of time, it determines whether a user frame is received from the outer loop port. A ring type redundant communication path control method comprising a step of inspecting and detecting a failure of a control module if a user frame is received. In the ring-type redundant communication path control method according to any one of claims 1 to 5,
The transfer device is
The device identifiers of all transfer devices connected to the ring-type redundant communication path are stored, and the device identifier sequence of the inner loop control frame and the device identifier sequence of the outer loop control frame of the identifier sequence storage unit are stored as the device identifiers of all transfer devices Detecting a double failure when there are a plurality of device identifiers not included in both, and
A ring-type redundant communication path control method including a step of blocking a control port when a double failure is detected.

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